1. Field of the Invention
The invention relates generally to devices and methods for improved fracturing and/or gravel packing operations within a wellbore. In more particular aspects, the invention relates to the protection of devices that are used to place gravel or proppants in such operations.
2. Description of the Related Art
There are times during the life of a well that it is necessary to flow granular or pelletized solid materials, in a slurry, into a wellbore in order to improve wellbore operation or to extend the life of the well. Two of the more common techniques are gravel packing and fracturing of a formation using a fracturing fluid having proppant therein. During gravel packing, gravel is pumped down a tubing string into a wellbore and placed, where desired, using a cross-over tool with suitable exit ports for placement of the gravel in desired locations within the wellbore. In fracturing operations, a fracturing agent is flowed into the wellbore under very high pressure to fracture the formation that immediately surrounds the borehole, thereby creating improved flowpaths for hydrocarbons to enter the wellbore from the surrounding formation. The fracturing agent, a fluid, often contains a proppant, which is in granular or pelletized form. Typical proppants includes peanut shells, sand, ceramics, and other materials known in the art. Proppants are flowed into the fractures created by the fracturing agent and remain there after the fracturing agent has been removed from the wellbore in order to help prop the fractures open and allow the improved flow to continue.
While gravel packing and fracturing operations are often necessary, they do create significant erosion wear upon the components of the production assembly as the gravel or proppant is flowed into the wellbore. Erosion damage to the production assembly, if significant, can result in a loss of production containment in the wellbore. One area that tends to receive the most severe damage is around the exit port where the solid material exits the crossover tool and enters the inside of the production assembly. In order to counter this significant wear damage, devices have been developed that are better able to withstand the wear associated with these operations. Typically, a wear sleeve or blast liner will be placed proximate the exit port, or the exit port will actually be disposed through this wear sleeve or blast liner. There is, however, some disagreement over the preferred composition of a wear sleeve or blast liner that should be used. Materials that are harder, and less subject to deformation, also tend to be more brittle. Additionally, regardless of the material that is used to form the sleeve or liner, the concentration of erosive forces upon the liner/sleeve will always tend to shorten the life of the placement components.
The present invention addresses the problems of the prior art.